GBS Guidelines

Contributor: S. Chapman, MD                                        Date: Feb 2020

Background: Group B streptococcus is the leading cause of newborn infection.  The primary risk factor for neonatal GBS early onset disease is maternal colonization of the genitourinary and gastrointestinal tracts.  Vertical transmission usually occurs during labor after rupture of membranes.  Fifty percent of women who are GBS-colonized will transmit GBS to their newborns and 1 to 2% of these newborns will develop GBS early onset disease.

Risk factors:

• Maternal colonization with GBS at time of labor or ROM
• GA <37 weeks
• Very low birthweight
• PPPROM of prolonged rupture of membranes (>18 hours)
• Intra-amniotic infection
• Young maternal age
• Maternal black race

Effective prevention of GBS early onset disease in newborns includes universal prenatal screening by vaginal–rectal culture, correct specimen collection and processing, appropriate intrapartum antibiotic prophylaxis, and coordination with pediatric health providers.

Recommendations:

• Universal antepartum screening for GBS at 36 0/7 – 37 6/7 weeks of gestation, unless GBS bacteriuria earlier in pregnancy or a previously GBS infected newborn
• All women with positive GBS vaginal–rectal cultures, GBS bacteruria in current pregnancy or prior child with invasive GBS disease should receive appropriate intrapartum intravenous antibiotic prophylaxis unless a pre-labor cesarean birth is performed in the setting of intact membranes.
• If GBS culture result is unknown when labor ensues, intrapartum antibiotic prophylaxis is indicated for women who have the following risk factors…threatened PTD, PPROM, ROM >18 hours, or suspected intra-amniotic infection (T>100.4 F)
• If patient presents in labor at term with unknown GBS colonization but reports a known history of GBS colonization in a previous pregnancy, consider intrapartum antibiotic prophylaxis as an informed consent process.

Treatment:

Penicillin G 5 million units IV load then 3 million units IV every 4 hours until delivery

OR

Ampicillin 2 g IV load then 1 g every 4 hours until delivery

For penicillin allergy:

• Low risk- Cefazolin and 2 g IV load then 1 g IV every 8 hours until delivery
• High risk- Request clindamycin susceptibility on laboratory requisition for vaginal–rectal culture done at 36- 37 weeks gestation.

-If Clindamycin susceptible, Clindamycin 900 mg IV every 8 hours until delivery

-If clindamycin resistant, vancomycin weight-based dosage of 20 mg/kg IV every 8 hours.  Maximum doses 2 g and minimum infusion time is 1 hour or 500 mg/30 min for a dose greater than 1 g.  Consider pharmacy to dose if any evidence of maternal renal impairment.

• Unknown risk-attempt penicillin allergy testing prior to labor

Although a shorter duration of recommended intrapartum antibiotics is less effective than > 4 hours of prophylaxis, obstetric interventions should not be delayed.

 

Special considerations:

Please see ACOG Committee Opinion for specific recommendations

• Management of women with preterm labor <37 0/7 weeks
• Management of women with PPROM
• Various obstetric procedures

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References

Prevention of group B streptococcal early–onset disease in newborns. ACOG Committee Opinion No. 797.  American College of Obstetricians and Gynecologists. Obstet Gynecol 2020; 135:e51-72.